The New AHA Recommendation Does Not Include Mouth-to-Mouth Breathing for lay rescuer.If you need to save a life, just press on the chest fast and hard 100 times a minute

In a major 2010 change, the American Heart Association said that rapid, deep presses on the chest of an adult cardiac arrest victim until help arrives, works just as well as standard CPR, which includes mouth-to-mouth breathing.
Experts hope bystanders now will be more willing to jump in and help if they see someone collapse. Hands-only CPR is simpler and easier to remember and removes a big barrier for people skittish about mouth-to-mouth breathing.

You only have to Call 911 and push hard and fast on the middle of the victim’s chest.

Hands only CPR calls for uninterrupted chest compressions 100 times a minute — until EMS workers take over or an automated external defibrillator is available to restore a normal heart rhythm.
This action should be taken only for adults who unexpectedly collapse, stop breathing and are unresponsive. The odds are that the person is having cardiac arrest.

A child who collapses is more likely to primarily have breathing problems, and in that case, mouth-to-mouth breathing should be used. That also applies to adults who suffer lack of oxygen from a near-drowning, drug overdose or carbon monoxide poisoning. In these cases, people need mouth-to-mouth to get air into their lungs and bloodstream.